Carrier-wave signaling system



Nor. 30 1926.

J. s. JAMMER CRRIER WAVE SIGNALING SYSTEM Fi1ed D90. 29, 1920 Jacok 5Jammer Patentecl Nov. 3,

INCOBPORATED, OF NEW' YORK, II.

Appliczition fi1ed December lhis invention relates t carrier wavesignaling systems and more particularly to sucl1 systems wherein two-wayoperation is provided over two-way channels between an ordinarytelephone line and a carrier wave transmission medium such as thenatural media used in radio Communications, an ordinary telephone ertelegraph transmission line, 01 a power transmission line.

In systcms of this general type it is customary to have an ordinary lOWfrequency telephone line normally connected to a twoway channel of acarrier wave terminal sta tion. 'lho low frequenc v line is connectedconjugately through a balariced transformer to the transmitting andreceivinp; circuits of the tw0-way channel. F0r testing or otherpurposes, it is often necessar v to disconnect the low frequency linefrom the carrier terminal channel, and for this purpose a jack 0rcontact arrangement is insertecl between the balanced transformer andthe low trequency line. With sucl1 an arrangement, unless somsprecaution is taken, the two way channe] will sing due to theunloalancing of the balanced transformer when the low freouency line isdisconnected.

It is an object of this invent-ion to prevent tle carrier cl1annel tromsingine or otherwise 1nis-iunctioninsr due to this discon nection of thelow frequenc; line. A tea ture of the invention is a jack and relayarrangement rvhereb v this result may be accomplished. Another featureis the accomplishment of this result b v short-circuiting the speechinput circuit of the modulator. A turther object is to provide anarrangement or short-circuiting the modulator which will function onl vwhen no substitute line or equivalent apnaratus is connected in place ofthe normally connected low fre quency line.

In ons emhodiment of the i1wention these objects are accomplished hyproviding a relav. through a normally open contact of Which the speechinput circuit of a.modu lator mar loe shortcircuited when desired. A lowfrequency line is terminated in a pair of jacks at the carrier terminalstation. The 10W frequency terminal of the two-way carrier chan1iel atthe same station is also terminated in a pair of jacks. These two pairsof jacks are normally s0 connectecl together as to form a continuoustransmission circuit between the low freone two-way quency line and thetwo-way carrier chann el. For call signaling tl1e modulator shortcrrcuiting relay is actuated. For ether purposes, hereinatter to bedcscribed, tliis jack arrangement permits the operation of the modulatorshort-circuiting relay when a plug is inse ted in the line jacksproviding thc carrier terminal jacks are normal.

This inventiou will be more clearly undcrstood trom a detaileddescription of one cmbodimcntthereot and li reterence to theaccompanying drawing. 'lhe clrawing illustrates a multiplex carriertelephone sy tem showinp; in some detail one complete two-waycarrierchannel. Another similar channel is merely indicated.

@ne terminal station 0lllf is shown, it being understood th at tl1erc isa similar distant cooperating station (notshown). 'lwo-way channels ofthe station shown coopcrate with correspcnding two-way cl1annels of thedistant station. The transmitting circuit of cl1annel in turn cooperatcsWith the receiv1ng circuit of the cooperating distant cl1annel, and viceversa.

Tlie terminal station iilustrated in t-lie drawing comprises a two-waycarrier channel CH transmittingr circuit TC ancl a receiving circuit forchannel CH are connected to a common line ML through a balancedtranstormer 5. These circuits are also connected to a two-wire lowfrequency line 2? through a 10W frequency balanced transtormer l.Balanced transtormers 4: and 5 have a high requenc net HFN and a loufrequency net Lllf l respectively connected to their line windincs. Tlieopposite terminals 01 the line windings of balanced transformer i areconnected tl1rough the normally closed back contacts of iiiiging relay 6to carrier terminal. jacks 7, A telephone station A is connected to alow frequency line L which terminates in a pair of jacks 8, 8. Jacks 7,7 and 8, 8 are connected together loy concluctors 9. so that, normally.a continuous transmission circuit extends trom station A over line Ltl1rough jacks 8. 8 conductors 9 jacks 7, tlnougli channel CH to thecommon line l'illl].

Transmitting circuit TC comprises a source of carrier Waies modulatorllil. and modulator hand filter ll IBF ii. speech input circuit tor themodulator M compriscs concluctors 10 wliicli connected betweon theseries winding of the balanced traittormer 1 and the modulator M. '1hereceiving circuit RC co1nprises a detector band filter DBF a detector D,a detector amplifier DA, a speech frequency transtormer 11, and a lowpass filter LPF connected to the bridge circuit of balanced transformer4. For signaling purpo-ses a signaling detector SD may be connected tothe output circuit of the detector amplifier DA to proxj-de signalingenergy tor relay 12.

Modulator hand filter MBF and detector band filter DBF are each adaptedto pass a broad band of requencies and may be ot the general typedescribed in Patents Nos. 1,227,113 and 1,227,111 to G. A. Camploelldated May 22, 1917. The constants of these filters are so chosen as topass the particular range of trequencies, which are being used tor theparticular receiving or trausmitting; circuit. In general the severalreceiving and transmittingcicuits will employ distinctive hands ofirequencies.

The 10W pass filter LPF is also ot the general type described in theabove mentioned Camploell patents and is adapted to suppress currentshaving frequencies above the highest essential frequency o;t voicecurrents and to transmit with suhstantially negligible attenuationcurrents of the highest essential voice fiequency and of all lowertrequencies.

The source of carrier waves O, the modulator M, the detector D, thedetector am'plifier DA and the signal detector SD may be of any suitableconstruction, b-ut preterahly each is of the wellknown three electrodethermionic va uum tube type.

Fo-r transmitting call signals to a distant station, relays 13 and 14.are provided. For receiving call signals from a distant station,signaling detector SD, relays 12, 6, and the lower winding of relay 3are provided.

A second two-way channel, CH is indicated,and as shovvn is alsoconnected to the common line ML through the loalanced transforrner 5. Onthe low requency side it terminates ina pair ot jacks 15, 15. A. secondlow requency telephone terminal station B is associated through a 10Wtrequency line L with a pair of jacks 16, 16 located at the carrierterminal station. These jacks are likewise connected together to torm acontinuous circuit trom telephone station B over low requency line Lthrough jacks 16, 16, jacks 15, 15, twoway carrier channel CH2, and thebalanced transformer 5 to the main line ML.

A modulator hand filter MBF and a detector band filter DBF are connectedrespectively in the transmitting and receving circuit-s ot two-waychannel CH These band filters are of the same general type as thecorresponding filters in channel CH differing only in their constants inorder to provide selectivity between thesereral carriet channels. Asshown, the modulator hand filters are connectved in series with eachother in a manner which is Well known and described in United StatesPatent No. 1,428,155, September 5, 1922, issued to: L.. E. Espensclriedand= H. A. rrel to form a common transmitting circuit. Similarly thedetector hand filters are connected in series according to the sameprinciple to form a common receiving circuit.

T he block T represents a test set terminating in a pair of plugs 17, 17whiclr. are adapted to connect with aairs or"" jacks as illustrated.Block TS may illustrate a tele phone set adapted for use with eitherlines L and L or with twoway carrier channel's CH and CH Sucli telephoneset nra=y terminate in a pair of plugs 18, 18 similiar to tliosepreviously described. A. patchi-ng oord" is also shown comprising theconductors 1.9 terminating at one end in a pair of plugs 20, 20 and atthe other in a pair of plugs 21, 21. These pairs of plugs are likewiseadapted te cooperate with the pairs of jacks as illustra-ted.

ccording to this invention, relay3 at its upper normally open backcontact is adapted upon ene-rgization to short-circuit the speech inputcircuit 10 of the modulator by closing the circuit through conductors22. Relay 3 may be energized by current in its upper winding, a circuittor which may be traced trom ground through battery 23, the upperwinding of relay 3, normally closed upper contact ofupper jack 7,conductor 21, nor- 1nally open contact of upper jack 8 to ground. Relay3 may also be energized by current in its lower winding, a circuit torwhich may be traced trom groundthrough battery 23, lower winding ofrelay 3, normally open back contact of relay 12 to ground. Tliis lasttraced circuit is provided to pre vent singing in the two-way channel CHwhile call signals are being received from a distant cooperatingstation.

The operation of the system under several conditions will now bedescriloed.

.The operation will first be descriloed in connection with callsignaling or ringing. VVith the connectionsas shown, it Will he assumedthat station A desires to call a distant cooperatin-g station (notshown). The operator at station A Will impress ringing current in awell-known manner on the line L which Will traverse 1ine L jacks 8, 8,conductors 9, jacks 7, 7, normal1y closed back contacts of relay 6,lower closed contact of relay 3, and windings of relay 13. Relay 13 willrespond theret-o by vibrating at the frequency of the ringing current,and cause the deenergization of relay 14 by opening its normally closedenergizing circuit at the normallyclosed back contact of relay 13. The

deenergization ot relay 1t places a shortcircut upon the oscillatoroutput circuit by closing a circuit to ground through its normally openfront contact now closed. In the normal operation of the system, theoscillator O causes a continuous flow of carrier waves to the main lineML through the modulator M, modulator band filter. MBF and loalancedtransformer 5. The short-cir cuiting of the oscillator O interruptstl1is normal flow of carrier waves as long as ringing current isimpressed upon the low frequency line L The action at the cooperatingdistant sta tion will now loe described in connection with the receivingcircuit RC of channel CII Carrier waves transmitted from the distantstation, which are normally present on the COII1II1OI1 line ML areimpressed upon the signaling detector SD from the balanced transformer5, detector band filter DBF detector D, and detector amplifier DA. Thesignaling detector SD functions to cause a flow of unidirectionalcurrent in relay 12 to normally hold open its back contact. Carrierwaves are prevented fro1n being impressed upon the bridge circuit ofbalanced transformer 4 by means of the 10W pass filter LPF.

During the time when the train of car rier waves is interrupted at thedistant transmitting station as just described, relay 12 is deenergized.Thereupon relays 3 and 6 are actuated by current rom batteries 23 and 25respectively, a circuit trom ground through battery 23, lower winding ofrelay 3 and back contact of relay 12 (now closed) to ground beingcompleted for relay 3 and another circuit trom ground, through battery25, winding of relay 6, the same back contact of relay 12 (now closed)to ground for relay 6. Relay 3 Which is quick acting places ashort-circuit tlirough conductors 22 upon the modulator input circuit 10to prevent modulating current trom entering the modulator therefrom.Relay 6, which is somewhat slower to act disconnects the 10W frequencyterminal jacks 7, 7 from the carrier channel CH and connects a source ofringing current 26 to the low ductors 27. Ringing current is thereforeimpressed upon the 10W frequency line L to operate a signaling device(not shown) at station A. When the 10W frequency con ductors 27 aredisconnected from the line windings of balanced transformer 41, carrierchannel CH is unloalancecl at the transformer 4, and singing wouldresult were it not for the short-circuiting of the modulator inputcircuit 10. ringng interval, carrier waves from the distant station areagain impressed upon the signaling detector SD to energize the relay 12Which allows relays 6 and 3 to loeconie deenergized, and the armaturesto fall back to tlieir normal positions. Rclay 6 is more quick torelease than relay 3. It thereore connects the line L to the carrierchannel CH before the shortcircuit is removed frequency con- At theclose of the from the modulator input circuit 10, thereby guarding thecircuit against 'alse operation due to charging current in the line Ldischarging through the modulator M and so into the carrier system as awhole. With the circuit as shown, such discliarge, if present, takesplace tl1rough the short-circuiting conductors 22 and the energy thereofexpends itse1f harmlessly in the resistance of the circuit.

In another situation now to be explained, the carrier channel OI-I isunloalanced and the modulator input circuit 10 is a ain shortcircuitedto prevent singing anc misfunctioning of the system. Such a situationarises when the low frequency line L is disconnected from the carrierchannel CH by the insertion of plugs such as 17, 17 into jacks 8, 8 fortesting purposes or the like.

When the plugs 17 17 are insertecl in the jacks 8, 8 the conductors 9are disconnected trom the line L at the normally closed contacts of thejacks 8, 8. By the same opera tion a circuit through the upper windingof relay 3 is completed. This circuit extends trom ground, throughbattery 23, upper winding of rela y 3, conductor 28, upper normallyclosed contact of upper jack 7, con ductor 24, normally open contact ofupper jack 8 (now closed) to ground. Relay 3, is actuated, and ashort-circuit as l1ereinbefore descriloed is placed upon the modulatorinput circuit 10 to prevent singing due to the unloalancing of channelCH Still another situation may arise. VVhile the line L is being usedfor test purposes or the like, it may be desiralole to connect anotherlow frequency line such as L to the carrier channel CH whereloy asubscriber at station B on line L may communicate over channel CH and itcooperating dis tant channel. To permit of this, jacks 7, 7 and 16, 16are connected together by a patching oord 19. Plugs 20, 20 are nsertedinto jacks 7,7 and plugs 21, 21 are inserted into jacks 16, 16. VVit-hplugs 17, 17 in jacks 8, 8 as hereinbefore describecl, channel CH cannotfunction due to the shortcircuit of the modulator input circuit 10. Theinsertion of plugs 20, 20 into jacks 7, 7, it Will be noted, removesthis short-circuit by opening the en'ergizing circuit of relay 3 throughits upper winding at the upper normally closed contact (now open) ofupper jack 7. Tlius the carrier channel CH is restored to normal, and itcan function exactly the same as though line L were connected to itinsteacl of line L It should be noted that the insertion of plup;s 21,21 in jacks 16, 16 Will disable channel CH by placing a short-circuitacross the modulator input of that channel in the same manner asdescribed in connection with channel CH whcn plugs 17, 17 are insertedin jacks 8, 8.

With ihecar1ier terininai apparatus anti 10W frequency iines in use asjust ciescriiceci, arrier channei CH may be restored te operatingcenciition, by the insertion of piugs 18, 18 int0 jacks 15, 15. By thisconnection channei CH niay be useci in connectien with apparatus '1S ortaiking purposes, testing purposes 01 the like.

Other combinations than those ciescribeci wiii be evident to thoseskiiieci in the art, but it Wiii be noted that in every case, when theieaiance of a tw0-way channei is tiestrcyeci, cieieterious efects suchas singing are preventeci by 1neans independent 0 the i3aiance of thechannei. It shouici also be notcci that, whiie ti1e channei is thus disabieci, it maybe restoreci t0 nern1ai operating conciition by theconnection of suitabie apparatus to the channei terminai jacks.

i Vhiie the citaiieci description of the invention has been confineci teits en1bocii1nent in a 1nuitipiex carrier wave signaiing systen1, etherembeciixnents there0f W'iii i0e evident t0 these skiiieci in the artanti the invention is to be iimiteci oniy by the scope of the appencieciclaims.

1Vhat is ciain1ed is:

1. A co1nrnon transn1ission iine, a twe- Way c0nnnunication circuitconnecteci thereto and having an inco1ning channei and an circuits eachaciapteci te be connecteci t0 said iine over saici communicationcircuit, 2111(i 1neans f0r shortcircuiting saici outgoing3; channei t0prevent singing in the connnunicationcircuit when none of saicisignaiing circuits are connecteci thereto.

2. A signaitransrnission circuit, a tweway communication channelconnecteci tiierete anti having an incorning and an ontgoing channei,ter1ninating 1neans for saici transmission circuit, a sec0ncitransmission circuit, ter1ninating 1neans for said seconri transmissioncircuit, anti means under the control of botirof saici ter1ninating1neans te ciisabie saici out-going channei.

3. In a carrier wave signaiing system. a

two-way carrier channei, terminating 1neans 0r saici channei, a 10Wfrequency iine, ter- 1ninating 1neans f0r saici iine, n1eans te connectsaid two ter1ninating ineans together te form a continuous transxnissioncircuit, anti 1neans uncier the controiof iooth saici terminating 1neansto ciisabie saici channei for twc-way communication.

1. In a signaiing system, signai wave modifying 1neans, a sigriaioriginating cir cuit, a contact arrangement ccnnecteri te saici signaiwave mociifying n1eans, a second contact arrangementconnecteci t0 saicisignai originating circuit, a connection between aici contactarrangements te operabiy associate saici signai wave modifying meanswith saici signai originating circuit, 1neans centroiieci by theoperation of saici second contact arrangement t0 ciisabie sairi signaiWave modifying 1neans, anci 1neans controiieci by the operation of saicifirst contact arrangement to prevent tiie ciisabiingethe signai waremcciifying 1neans.

5. in a carrier wave signaiing systen1, a two-way carrier channei, apair of jacks 10r terminating saici channei, a 10W requency line, pairof jacks or terminating said iine,

conductors connecting saici 1ine jacks anci channei jacks toget-her t0forni a coniinnous transmission circuit, anti a reiay uncier the controiof both saici iine 21I1Ci Channei ter1ni nat-ing jacks te ciisabie saicichannei 0r twoway communication.

6. In a signaiing syste1n, signai wave meciifyingr 1neans, a signaioriginating circuit, a pair 0 jacks connecteci tesaici WIVG 1nociiiyingmeans, a sec0nci pair of jacks conne ieti te saici signai originatingcircuit, conciuctors connecteci te boti of sairipairs of jacks t0operabiy asscciate saici sigriai wave medityinq n1eans witi1 saicisignai originating circuit, a pair 0 piugs, 1neans controiieci by theinsertion of saici piu9;s into the jacks connecteci t0 saici signaioriginating circuit te ciisabie saici signai waje mociifying 1neans aseconci pair of piugs, anti means ccntroiied by tie 1nsertion 0 sarciseconci pair of piugs into the jacks connecteci t0 saici signai wave1nociifying rneans to prevent 'the ciisaiciing of the signai wave-1nociifying n1eans.

7. In a signaiing system, a 10W frequency iine, a two-way carrierchannei comprising an outgoing anci an incmning branci1 connected inccnjugate reiation with saici iine, 1neans at a piuraiity of points f0rdisconnecting said iine rr01n saici channei, an i 1neans operateci inconjuncci0n with the operation of each of saici disconnecting 1neans t0ciisaioie saici outgoing channei.

8. A combination in accorciance with ciai1n 7 in which one of saiciciisconnectinp 1neans is aciapteci te ciisconnect the 10W frequency linefrom the carrier channei anti t0 appiy te saici iine currents ofsignaiing requency;

9. A two-way connnunication system in ciuciing a 10w frequency iine, atwo-way carrier hannei c01nprising an outgoing anti an inco1ning branchconnecteci in conjugate re iation with saici iine, said cutgoing carrierb-ranch inciuciing a source 0 carrier frequency waves llCi a 1nociuiatortherefor, n1eans iocateri at a piuraiity of pcinis in saici iine forciisconnecting saici iine 'fr0n1 saici carrier channe-i. a reiayaciapted te short circuit saii modulator, anti naeans' 0r operatingsaici reiay in conjunction with the 0peration of any one 0 sa1cici1sconnect1ng 1neans.

In witness whereof, I h-ereunto subscriice 1ny name this 24th ciay 01December A. D., 1920.

JACOB s. JAMMER

